Rotating gas turbine blade and gas turbine with such a blade

Abstract

A rotating gas turbine blade is disclosed which includes an airfoil with a suction side and a pressure side, the airfoil extending in a radial direction from a blade root to a blade tip. The blade tip includes a tip shroud, the airfoil having internal cooling passages for a cooling medium, which extend through the tip shroud. Outlet ports are provided above a selected internal airfoil cooling passage for the cooling medium to be ejected above the tip shroud in a direction of the blade's pressure side. Dust accumulation is avoided at the tip end of the selected internal cooling passage.

The invention claimed is: 
     
       1. A rotating gas turbine blade, comprising:
 an airfoil with a suction side and a pressure side, said airfoil extending in a radial direction from a blade root to a blade tip, wherein said blade tip includes a tip shroud, said airfoil having internal cooling passages for a cooling medium, which extend through said tip shroud, and outlet ports are provided above a selected internal airfoil cooling passage for said cooling medium to be ejected above said tip shroud in a direction of the blade's pressure side, said tip shroud is provided with two or more fins extending in parallel to each other on an upper side of said tip shroud in a circumferential direction, and interspaces are defined between neighboring of said fins, wherein holes for avoiding dust accumulation are provided at a tip end of said selected internal cooling passage, and wherein said interspaces are provided with elevated areas, and said outlet ports and said holes for avoiding dust accumulation are disposed in said elevated areas. 
 
     
     
       2. The rotating gas turbine blade as claimed in  claim 1 , wherein said holes for avoiding dust accumulation extend in a radial direction from said selected internal cooling passage to an outside above said tip shroud. 
     
     
       3. The rotating gas turbine blade as claimed in  claim 2 , wherein said internal cooling passages are cast in a core, which is held in position by core exits, which connect the core to a mould through said tip shroud, and holes generated by said core exits are said dust holes. 
     
     
       4. The rotating gas turbine blade as claimed in  claim 1 , wherein said outlet ports are machined ports in said tip shroud. 
     
     
       5. The rotating gas turbine blade as claimed in  claim 4 , wherein said outlet ports are oriented such that said cooling medium will be ejected with a significant component in a rotating direction of the blade. 
     
     
       6. The rotating gas turbine blade as claimed in  claim 5 , wherein in said outlet ports a turning of an internal flow from upwards along the blade's longitudinal direction is provided by a curved shape towards a desired direction. 
     
     
       7. A gas turbine, comprising:
 a rotor with a plurality of rotating gas turbine blades, wherein at least one of these rotating gas turbine blades are rotating gas turbine blades according to  claim 1 . 
 
     
     
       8. The rotating gas turbine blade as claimed in  claim 1 , wherein the two or more fins comprises three parallel fins, which extend along the circumferential direction. 
     
     
       9. The rotating gas turbine blade as claimed in  claim 1 , wherein the cooling medium is compressed air. 
     
     
       10. The rotating gas turbine blade as claimed in  claim 1 , wherein the tip shroud of the rotating gas turbine blade is part of a partially closed or closed ring when each of the plurality of rotating gas turbine blades of a same turbine stage are mounted on the rotor. 
     
     
       11. A gas turbine, comprising:
 a rotor with a plurality of rotating gas turbine blades, each of the plurality of rotating gas turbine blades having an airfoil with a suction side and a pressure side, said airfoil extending in a radial direction from a blade root to a blade tip, wherein said blade tip includes a tip shroud, said airfoil having internal cooling passages for a cooling medium, which extend through said tip shroud, and outlet ports are provided above a selected internal airfoil cooling passage for said cooling medium to be ejected above said tip shroud in a direction of the blade's pressure side, said tip shroud is provided with two or more fins extending in parallel to each other on an upper side of said tip shroud in a circumferential direction, and interspaces are defined between each of said fins, and elevated areas within each of said interspaces, and wherein holes for avoiding dust accumulation are provided at a tip end of said selected internal cooling passage and extend in a radial direction from said selected internal cooling passage to an outside above said tip shroud, and wherein said outlet ports and said holes for avoiding dust accumulation are disposed in said elevated areas. 
 
     
     
       12. The gas turbine as claimed in  claim 11 , wherein said internal cooling passages are cast in a core, which is held in position by core exits, which connect the core to a mould through said tip shroud, and holes generated by said core exits are said dust holes. 
     
     
       13. The gas turbine as claimed in  claim 11 , wherein said outlet ports are machined ports in said tip shroud. 
     
     
       14. The gas turbine as claimed in  claim 11 , wherein said outlet ports are oriented such that said cooling medium is ejected with a significant component in a rotating direction of the blade. 
     
     
       15. The gas turbine as claimed in  claim 14 , wherein in said outlet ports a turning of an internal flow from upwards along the blade's longitudinal direction is provided by a curved shape towards a desired direction. 
     
     
       16. The gas turbine as claimed in  claim 11 , wherein the two or more fins comprises three parallel fins, which extend along the circumferential direction. 
     
     
       17. The gas turbine as claimed in  claim 11 , wherein the cooling medium is compressed air. 
     
     
       18. The gas turbine as claimed in  claim 11 , wherein the tip shroud of each of the plurality of rotating gas turbine blades is part of a partially closed or closed ring when each of the plurality of rotating gas turbine blades of a same turbine stage are mounted on the rotor. 
     
     
       19. The gas turbine as claimed in  claim 11 , wherein each of the plurality of rotating gas turbine blades has a fir tree configuration. 
     
     
       20. The gas turbine as claimed in  claim 11 , further comprising:
 a casing, the casing configured to enclose the rotor and the plurality of rotating gas turbine blades.